Roger Federer and Novak Djokovic, the top two players in the world, set up a showdown for the Cincinnati Masters title after cruising to semi-final victories on Saturday.

The gap between the leading four, which also contains Rafa Nadal and Andy Murray, and the chasing pack was again evident as Djokovic beat Argentine Juan Martin del Potro 6-3 6-2 before Federer saw off fellow Swiss Stanislas Wawrinka 7-6 6-3.

World number one Federer is chasing a fifth title in Cincinnati while Djokovic is hoping to claim his first at the Ohio venue, having lost three times in the final including last year when he retired injured in the second set against Murray.

The Serb avenged his defeat by Del Potro in the bronze-medal match at the London Olympics earlier this month when he powered into his 22nd Masters 1000 final.

A tight first set turned in Djokovic's favour when sixth seed Del Potro, who was unable to capitalise on any of the six break points he had in the match, double-faulted to let his opponent go 4-2 ahead.

It was relatively straightforward in the second set after Djokovic, who won last week's Toronto Masters crown, took advantage of some loose returns to break and go 2-1 up.

Federer has a 15-12 advantage in matches with Djokovic and the Serb knows he faces a stern test against the Wimbledon champion.

"We all know how good he is, especially in the later stages of events, and here conditions are quite fast so I think it's suited to his style," Djokovic told reporters.

"We have played so many matches against each other. It's always a big challenge when you play a big rival of yours."

Federer needed a tiebreak to secure the first set against Wawrinka but once he broke in the second to go 4-2 up he quickly raced to victory.  

- Reuters